A longitudinal, observational, observational design, with multiple measurements will be used to: (1) examine the relationship between psychometric health status measures, health utility measures, and clinical symptoms and conditions in HIV infected patients; (2) examine the responsiveness of psychometric health status and health utility measures to changes in clinical symptoms and condition in HIV infected patients; and (3) describe the changes in psychometric health status and health utility measures in HIV infected patients over time. A longitudinal design is selected to enable the evaluation of inter- and intra-individual changes over time. A consecutive sample of 400 HIV infected patients receiving medical care at 7 infectious disease or primary clinics will be asked to participate in the study. Participation in the study will be voluntary. Health status and utility data will be collected during personal interviews every four months for 12 months, or until the patient dies. Eligibility criteria include documented HIV infection, age greater than 18 years, and expected survival of at least 4 months. Patients will be excluded if they are blind, illiterate, too severely cognitively impaired to complete personal interviews, or completely bedridden. The 7 clinical centers are located in the Baltimore-Washington area, and provide medical care for approximately 5,100 patients with HIV disease. Clinic patient demographic characteristics are representative of HIV infected patients in Baltimore and Washington, D.C. (21% female, 60% black). Measures of general health status, depression, neurocognitive functions, health utility and HIV- related symptoms will be collected during the interviews. Data on clinical status, symptoms and severity of illness will be abstracted from medical records. Health status, depression, health utility and neurocognitive status outcomes will be compared between patients with asymptomatic HIV disease, symptomatic HIV disease, and AIDS. Statistical analyses will examine between group and within group changes in health status and utility measures. Multivariate analysis and structural equation models will be used to analyze the longitudinal data on the relationship between health status, utility and clinical variables. The study is intended to: (1) explore methodological issues regarding psyhometric health status and health utility measures; (2) provide new information on the progression of HIV disease in terms of functional status and psychological well-being; (3) to develop health utility assessment instruments that can be used for evaluations of new medical treatments for HIV disease; and (4) examine the clinical responsiveness of health status measures to changes in clinical sites.